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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <functional>
#include <memory>
#include <mutex>
#include "flutter/common/task_runners.h"
#include "flutter/fml/time/time_point.h"
namespace flutter {
/// Abstract Base Class that represents a platform specific mechanism for
/// getting callbacks when a vsync event happens.
class VsyncWaiter : public std::enable_shared_from_this<VsyncWaiter> {
using Callback = std::function<void(fml::TimePoint frame_start_time,
fml::TimePoint frame_target_time)>;
virtual ~VsyncWaiter();
void AsyncWaitForVsync(const Callback& callback);
/// Add a secondary callback for the next vsync.
/// See also |PointerDataDispatcher::ScheduleSecondaryVsyncCallback|.
void ScheduleSecondaryCallback(const fml::closure& callback);
static constexpr float kUnknownRefreshRateFPS = 0.0;
// Get the display's maximum refresh rate in the unit of frame per second.
// Return kUnknownRefreshRateFPS if the refresh rate is unknown.
virtual float GetDisplayRefreshRate() const;
// On some backends, the |FireCallback| needs to be made from a static C
// method.
friend class VsyncWaiterAndroid;
friend class VsyncWaiterEmbedder;
const TaskRunners task_runners_;
VsyncWaiter(TaskRunners task_runners);
// Implementations are meant to override this method and arm their vsync
// latches when in response to this invocation. On vsync, they are meant to
// invoke the |FireCallback| method once (and only once) with the appropriate
// arguments. This method should not block the current thread.
virtual void AwaitVSync() = 0;
void FireCallback(fml::TimePoint frame_start_time,
fml::TimePoint frame_target_time);
std::mutex callback_mutex_;
Callback callback_;
std::mutex secondary_callback_mutex_;
fml::closure secondary_callback_;
} // namespace flutter